5 results about "Heterodyne interferometry" patented technology

This invention discloses a laser linewidth measurement device and method based on switchable channel delay self-heterodyne interferometry, belonging to the field of laser linewidth measurement technology. The laser to be measured is incident on a first fiber coupler via an isolator and splits into two paths: one path enters a computer-controlled first and second optical switches via a three-port fiber circulator, switching between different lengths of delay fiber via the first and second optical switches, rotating the polarization state by 90° via a Faraday rotating mirror before returning along the original path, and then restoring the original polarization state via a polarization controller; the other path undergoes frequency shifting via an acousto-optic frequency shifter. The two paths are combined via a second fiber coupler to generate a beat frequency optical signal, which is then acquired by a photodetector for photoelectric conversion and a spectrum analysis module. The computer fits the beat frequency power spectrum corresponding to different delay lengths to obtain the laser linewidth to be measured. This invention has strong anti-interference capabilities and can simultaneously acquire Lorentz linewidth, Gaussian linewidth, and composite linewidth, with a wide linewidth measurement range.

This invention belongs to the field of three-degree-of-freedom pose measurement technology, and relates to a single-beam three-degree-of-freedom pose measurement method and device based on heterodyne interferometry and self-collimation. The measurement method includes the following steps: Step 1: A laser beam is split into two beams with a certain frequency difference; Step 2: In the self-collimation module, the laser is split into a first reference beam and a first beam; the first beam is modulated, reflected, and then modulated again to split into a first measurement beam and a second beam; the second beam is modulated to a first photoelectric detection module; Step 3: In the heterodyne interferometry optical path, the laser is split into a second reference beam and a third beam; the third beam is modulated, reflected, and then split into a second measurement beam and a fourth beam; the two reference beams are merged to form a first interference beam, and the two measurement beams are merged to form a second interference beam; Step 4: A circuit module acquires the angle and displacement; The measurement device includes an optomechanical module, a target under test, and a circuit module. Using the above scheme, displacement and angle are measured simultaneously.

A heterodyne interferometer device and method based on wavefront regulation target mirror belong to laser interferometer measurement technical field, the present application solves the problem of insufficient system interference keeping ability under the condition of large angle deflection of target mirror. The device comprises a heterodyne interference mirror group and a wavefront regulation target mirror, the heterodyne interference mirror group separates a bundle of input light beams into a first measurement light beam and a first reference light beam, and separates another bundle of input light beams into a second measurement light beam and a second reference light beam, the wavefront regulation target mirror is installed on the measured object, and the second measurement light beam is reflected to form a return measurement light beam and returns to the heterodyne interference mirror group, when the measured object occurs angle deflection such as pitching or yawing in the movement process, the wavefront regulation target mirror deflects synchronously with the measured object, the return measurement light beam is parallel to the second measurement light beam, the change of the return measurement light beam caused by large angle deflection of the wavefront regulation target mirror is more manifested as the position translation of the optical axis, thereby weakening the angle mismatch and wavefront mismatch.

The invention discloses a vacuum temperature measuring device based on heterodyne interference, which is used for measuring tiny temperature fluctuation in a closed heat insulation space in a non-contact and high-precision manner, and belongs to the technical field of precision measurement. The device comprises a double-frequency heterodyne interferometer, a heat insulation box body, a vacuum cavity for accommodating the heat insulation box body and an aluminum pipe arranged in the heat insulation box body. Double-frequency orthogonal polarized light emitted by an interferometer located outside the vacuum cavity is split into reference light and measuring light through the optical assembly, and the reference light and the measuring light are reflected by the semicircular reflectors at the two ends of the aluminum tube respectively and then are combined for interference. The optical path change caused by thermal expansion and cold contraction of the aluminum pipe is calculated by detecting the phase change of the interference signal, and the temperature change in the heat insulation box body is inversed in combination with the thermal expansion coefficient. The device operates in vacuum, avoids air refractive index interference, has common-mode noise suppression capability, and is suitable for gravitational wave detection and other high-precision temperature measurement scenes.

This invention relates to a method and system for self-identification and compensation of errors in a three-degree-of-freedom heterodyne interferometry system, belonging to the field of laser interferometry technology. The method includes acquiring original axial displacement, pitch angle, and yaw angle measurement data; establishing a system error model that includes at least one of zero-position error, displacement angle coupling error, cosine error, channel drift error, and environmental drift error; fitting self-identification error compensation parameters based on initial state, preset small angle movements, short-stroke displacement movements, static output correlation, or multiple sets of data; statistically analyzing zero-position changes, drift trends, or residual changes during operation according to a sliding time window, updating drift compensation parameters, and using the current set of compensation parameters to perform online compensation on the original three-degree-of-freedom measurement results. This invention effectively improves the system's startup efficiency, multi-degree-of-freedom coupling error compensation capability, operational drift self-updating capability, and long-term measurement stability.